The present invention concerns an improved device for positioning and covering original documents on the illumination plane of a reprographic machine of the type in which the original is laid on the said plane during the exposure phase. In such a machine the original which is to be copied is laid over a transparent plane, the illumination plane, and there illuminated by a light source to obtain a reflected optical image on a photo-sensitive surface.
With a view to covering the illumination plane when the machine is not in use, to prevent external light from penetrating into the optical system during the reproducing operations and internal light from affecting the eyes of the operator, and finally to fix the original in position on the illumination plane, particularly in those machines in which the plane is carried by a mobile carriage during the copying operation, the machine is normally provided with a covering flap which may be of various types. These flaps are usually made of rigid metallic or flexible plastics material and are opaque in order to achieve the ends mentioned above.
Many of these, however, have the drawback of encouraging the operator, when several consecutive copies are being made, to forget and leave on the illumination plane the last original which has been copied. A result of this is that the operator frequently omits to make use of the flap when he is making copies of several orginals, thus avoiding the troublesome opening and closing of the covering flap, with consequent deterioration of the quality of the copies obtained.
Also, with particular reference to those machines in which the illumination plane is supported on a carriage, which moves relative to a fixed optical system, and when using originals of appreciable thickness, in particular books, many of the covering flaps are not capable of ensuring sufficiet pressure on the original to prevent displacement during movement of the carriage, with resulting loss of definition of the copies obtained.